Lifting-jack



(No Modex.) i J. S. KIRKWGOD..

LIFTING JACK.

Patented Feb. 20,1883.

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UNITE STATES ArnNT intron.

.LIFTINGeJAClL SPECIFICATION forming part of Letters Patent No. 272,837,dated February 20, 1883.

Application filed September 23, 1882. (No model.)

To all whom it 'may concern:

Be it known that I, JOSEPH S. KIRKwooD, of McKeesport, in thecountyofAllegheny and State of Pennsylvania, have invented certain newand useful lmprovementsin Lifting-Jacks; and I do hereby declare thatthe following is a full, clear, and exact description of the invention,which will enable others skilled in the art to which it appertains tomake and use the same, reference being had to the accompanying drawings,which form a part of this speoication, in which- Figure l is a partlysectional elevation of my-improved lifting-jack. Fig. 2 is a front viewof the same at the pawls.

This invention relates to lifting-jacks; and it consists in theconstruction and combination of parts, substantially as hereinafterfully described and claimed.

In the drawings, AA are the two side bars, grooved to receive thelifting or rack bar B, which is provided with the teeth a, and,if'desired, the foot b. A heavy bolt .or pin, c, passes across the jackand through the sides A, and on this is suspended a bifurcated link, d,the. pivotal part ot' the link to the pin c being in the shape of asolid barrel bored to receive the pin c. At the lower ends of the twoforks of link d the socket D of the lever is pivoted by the pin e, andthe metal ofthe socket D is extended to form the nose f, as shown. Bythis construction the lever is hung on a movable or pivotallysuspendedfulcrum, so that it may be disengaged from the teeth of the bar B andlowered for a fresh hold on the bar. At the same time the suspension issuch that the normal tendency of the fulcrum e is to gravitate to suchposition that the levernose f will engage one of the teeth a.

At a point in sides A below the lever and fulcrum I pivot two pawls, gand h, respectively-one shorter than the othereach about halt' the wid hof the rack-teeth c. While these may be pivoted on a simple pin, Iprefer the form shown. Pawl g has a short trunnion, t',

taking through one ofthe sides A, and a long trunnion,'k, reaching overthrough the opposite side A, andy provided with the wrenchsquare l.

Before putting the parts together the short pawl h, which is suitablybored out, is slipped upon the long trunnion 7s, upon which it revolvesfreely. Pawl gis longer than pawl h by about a distance equal to halfthe pitch of the teeth a in bar B. Both pawls are so weighted as togravitate toward bar B when on that side of a vertical line throughtrunnions k. Fig. 1 shows the parts in such position that the lever iselevated, ready to be depressed t'or lifting` the load. 0n depressingthe lever the bar B is elevated, and the t'ulcruin e swings inwardly asthe nose j' moves upwardly with the bar B. When the lever D hasaccomplished half its stroke the short pawl h falls in under the tooth cof the bar B, and` at the end of the stroke pawl g drops in under thesame tooth. This enables me to space the teeth a much farther apart thanis usual, and make them much heavier and stronger for railway and otherpurposes requiring great strength. The result of the two pawls is, infact, the same as if there were but one pawl and the rack-teeth wereonly half as far apart, as one pawl acts alternately with the other.

In order to lower the bar B, it is raised slightly to release the pawls,and then the latter can be thrown out. To el'ect this most readily 1 seta handle, m, on trunnion 7c at l, and ou pawl lL, I set a pin, n, whichis struck by some abutment or projection on the hub of pawl g. In thedrawings I show the pin u operating in a recess, p, on pawl g andengaging the ends thereof. By turning the handle m pawl g is thrown pastthe center backwardly,

`and striking the pin n throws the pawl h also outof engagement, sothat, when desired, one movement ot' the handle m suffices to throw bothpawls out.

If desired, when the load is light, one of the pawls may be thrown backsufficiently to allow the jack to be operated with only the remainingpawl.

I claim as my inventionl. In a lifting-jack, in combination with thesides A and sliding rack-bar B a, a lever, D, pivoted on a fulcrum. d e,swinging on an axis above the axis ot' the fulcrum e, andadapted to engage the rack-bar, substantially as described.

2. In a lifting-jack, the combination of the sides A, bar B a, pin c,bifurcated `link d, pin e, and lever D, having nosef, substantially asdescribed.

IOO

3. In alifting-jaek,the combination of'toot-hed In testimony that Iclaim the foregoing as barBand two grdvitatingpawls,gh,oneo`said my ownI have hereto aixed my signature in lo pawls being shorter than theother, substanpresence of two Witnesses.

Lially as described. y 5 4. In a lifting-jack, the combination of pawiJOSEPH S' KIRKWOOD g. having recess p and trnnnion k, with pnwlWitnesses: h, having pin n, and means for' rotauing said LEWIS HANEY,pawl g, substantially as described. l J. A, SMITH.

